The scroll will not return to its scroll temple unless a player returns it.

There are timers where a scroll will "reset" to its last location after being carried (or dropped on the ground) for a certain period of time.

So if a scroll was taken from its temple and not placed in any keep before the timer runs out, it will reset to its scroll temple.

The only other condition is when a scroll has been placed in a keep, and the faction that owns the scroll captures the keep. If someone picks up their faction's scroll (scroll 1) and then a captured enemy scroll is placed in the keep (scroll 2) -- if the timer runs out on the scroll (1) before it returned to its temple -- and since it cannot return to the last keep it was placed in because there is another scroll (2) there -- it will return to its temple. Although this may be buggy. I seem to recall seeing two scrolls in one keep before, but I don't know the conditions that caused it. (Maybe a scroll resetting to a keep at the same moment another scroll is being placed in the same keep.)

When it was possible to Ambush or chain pull through keep doors -- or DK leap into certain keeps -- there were times someone could solo capture a scroll without ever capturing the keep. You could also literally jump into keeps by gaining mega speed when casting a root on a guard while having the templar-style reflect bubble from a guard, and then using it to launch yourself up an incline. However, aside from being absurd and hilarious, it really hard to do in a controlled way, and you usually just died from fall damage. I am talking about SUPER mega speed, nearly uncontrollable, like you could launch yourself and "fly" halfway across the map (to your death of course). Whereas ambushing into a keep was so easy to do it mostly happened by accident. (None of these methods work anymore.)

Or still today, in the event someone was hiding somewhere in a keep, or possibly logged back into an enemy keep holding a scroll. They could grab it then jump out of the keep. (Usually, this would happen in large home keeps.) There may be some new method to extract scrolls from keeps without flipping them first, but I am unaware of it and couldn't post about it even if I were.